1. Field of the Invention
The present invention relates to a unitary air conditioner widely used in North America, and, more particularly, to a unitary air conditioner in which a plural-stage outdoor unit is operated by means of a 1-stage thermostat. Also, the present invention relates to a method of controlling variable operation thereof.
2. Description of the Related Art
FIG. 1 is a control circuit block diagram of a conventional 1-stage unitary air conditioner showing connection of principal circuit terminals.
As shown in FIG. 1, the 1-stage unitary air conditioner is constructed such that the 1-stage unitary air conditioner receives an operation signal or a stop signal from a 1-stage thermostat 11, which is mounted in a room, for operating a 1-stage indoor unit 13 and a 1-stage outdoor unit 15.
The 1-stage unitary air conditioner with the above-stated construction is an air-conditioning system widely used as one of household appliances in North America, such as the United States of America. According to an ON/OFF operation signal from the 1-stage thermostat 11, the 1-stage indoor unit 13 and the 1-stage outdoor unit 15 are turned ON/OFF while the capacities of the 1-stage indoor unit 13 and the 1-stage outdoor unit 15 are not changed. In the 1-stage indoor unit 23 is mounted an indoor fan 17, which is rotated such that flow rate of air can be adjusted to high, middle, and low flow rates.
Recently, energy saving and more convenient heating and cooling operation have been increasingly required. To this end, a 2-stage thermostat, by which the operation of the air conditioner is controlled in a high or low operation stage, has been proposed.
FIG. 2 is a control circuit block diagram of a conventional 2-stage unitary air conditioner showing connection of principal circuit terminals.
As shown in FIG. 2, the 2-stage unitary air conditioner comprises a 2-stage thermostat 21. The 2-stage unitary air conditioner is constructed such that a 1-stage indoor unit 23 and a 1-stage outdoor unit 25 are operated in a high or low operation stage, while the capacities of the 2-stage indoor unit 23 and the 2-stage outdoor unit 25 are changed, according to a high operation signal Y2 or a low operation signal Y1 from the 2-stage thermostat 21. In the 2-stage indoor unit 23 is mounted an indoor fan 27, which is rotated such that flow rate of air can be adjusted to high, middle, and low flow rates.
However, the above-described conventional 1-stage unitary air conditioner is constructed such that the 1-stage indoor unit 13 and the 1-stage outdoor unit 15 are connected to the 1-stage thermostat 11. Consequently, it is difficult to connect the 2-stage indoor unit 13 or the 2-stage outdoor unit 15 shown in FIG. 2 to the 1-stage thermostat 11. In other words, it is difficult to connect a multiple-stage indoor unit or a multiple-stage outdoor unit to the 1-stage thermostat 11.